Digital subscriber line (DSL) technology is commonly utilized to provide internet-related services to subscribers, such as, for example, homes and/or businesses (also referred to herein as users and/or customers). DSL technology enables customers to use telephone lines (e.g., ordinary twisted-pair copper telephone lines used to provide Plain Old Telephone System (POTS) services) to connect the customers to, for example, a high data rate broadband Internet network, broadband service and/or broadband content.
A service provider of a DSL service can use information such as loop length, cable gauge(s), presence of bridged tap(s), location of bridged tap(s), lengths of bridged tap(s), noise on the line, shorts, opens, etc. for trouble detection, trouble isolation and/or trouble prevention. Alternatively or additionally, it may be useful to have similar information concerning the telephone line before DSL service is offered, sold and/or provisioned to a potential DSL subscriber, from the service provider's location to the subscriber's location. Information such as that mentioned above is measured for the telephone line between the service provider's location and the subscriber's location. Existing line testing methods would disrupt the operation of the DSL line. For example prior art Single Ended line (SELT) testing methods are performed by sending a probe signal on the DSL lines, and measuring the reflection in order to estimate line characteristics, such as Return Loss or Line Impedance. This probing is done by disabling the operation of the DSL connection and performing the SELT testing. This would disrupt the DSL line operation, which would cause interruption of the DSL service to the customers. Therefore SELT testings are done typically during new customer signups, or when the DSL line has a problem. This would avoid causing service disruptions, however it prevents the service provider from having an up-to-date information on the status of the line.
Embodiments of the present invention overcome the above problems. The present invention provides methods and systems for performing DSL line testing, without disrupting the operation of the DSL line connection that is being tested. Therefore, it enables service providers to be able to probe the DSL line at any time, in order to have up-to-date information on the status of the DSL lines.
A line testing device (i.e. tester), operative to be located at a customer premises, causes the transmission of a probing signal into at least one telephone line. The tester computes a parameter that represents a characteristic of at least one telephone line based upon at least a measured reflected probing signal. Using any of a variety of method(s), technique(s) and/or algorithm(s), the testers compute the characterizing parameter(s) from the measured reflected probing signal. For example, with knowledge of what probing signal was transmitted, and given a received and/or measured reflected signal, a tester can, for example, compute an echo path response, detect the presence of a bridged tap, characterize a detected bridged tap, estimate a loop attenuation, and/or determine any suitable telephone line characteristic. In some circumstances, the measured reflected signals at the customer end of a telephone line will include a much greater level of detail about a customer premises environment and/or the telephone line than would be available from reflected signals at the other (e.g., CO or RT) end. Therefore, the tester provides an enhanced level of detailed diagnostics by performing one or more line test(s) from the customer premises 106.
While the following disclosure references the example digital subscriber line (DSL) system and/or the example of FIGS. 1-7, the methods and apparatus described herein may be used to characterize telephone lines for any variety, any size and/or any topology of DSL system. For example, a DSL system may include more than one DSL access multiplexer (DSLAM) located in more than one location and may include any number of telephone lines, DSL maintenance devices, testers, DSL modems and/or testers. Also, for example, at customer premises, a plurality of modems could terminate a plurality of telephone lines and share a single or a plurality of testers, data analyzers and/or computers. Additionally, although for purpose of explanation, the following disclosure refers to example systems, devices and/or networks illustrated in FIG. 1A, any additional and/or alternative variety and/or number of communication systems, devices and/or network(s) may be used to implement a DSL communication system and/or provide DSL communication services in accordance with the teachings disclosed herein. For example, the different functions collectively allocated among a DSL management center, a DSL access multiplexer (DSLAM), a DSL modem, a tester, computer, and/or a data analyzer as described below can be reallocated in any desired manner.
As used herein, the terms “user”, “subscriber” and/or “customer” refer to a person, business and/or organization to which communication services and/or equipment are and/or may potentially be provided by any of a variety of service provider(s). Further, the term “customer premises” refers to the location to which communication services are being provided by a service provider. For an example public switched telephone network (PSTN) used to provide DSL services, customer premises are located at, near and/or are associated with the network termination (NT) side of the telephone lines. Example customer premises include a residence or an office building.
As used herein, the term “operative” may describe an apparatus capable of an operation and/or actually in operation. For example, an apparatus operable to perform some function describes a device turned off yet is capable of performing an operation, by virtue of programming or hardware for example, and/or a device turned on and performing the operation. The term “signal” typically refers to an analog signal, the term “data” typically refers to digital data and the term “information” may refer to either an analog signal and/or a digital signal although other meanings may be inferred from the context of the usage of these terms.
As used herein, the term “service provider” refers to any of a variety of entities that provide, sell, provision, troubleshoot and/or maintain communication services and/or communication equipment. Example service providers include a telephone operating company, a cable operating company, a wireless operating company, an internet service provider, or any service that may independently or in conjunction with a DSL service provider offer services that diagnose or improve the DSL service.
As used herein, the term “subscriber equipment” refers to any equipment located at and/or in a customer premises for use in providing at least one subscriber service. The subscriber equipment may or may not be potentially available for additional purposes. While subscriber equipment is located at and/or in a customer premises, such equipment may be located on either side and/or both sides of a NT and/or any other network ownership demarcation. Subscriber equipment may be owned, rented, borrowed and/or leased by a subscriber. Subscriber equipment may be owned and entirely controlled by the service provider. For example, subscriber equipment could be owned by a service provider and the subscriber only plugs into a connector and has no other access and/or interaction with the device. Subscriber equipment is generally available to and/or accessible by the subscriber and may be acquired and/or obtained by the subscriber via any of a variety of sources including, but not limited to, a retailer, a service provider, and/or an employer. Example subscriber equipment includes a personal computer (PC), a set-top box (STB), a residential gateway and/or a DSL modem located at and/or in a subscriber's residence by which the subscriber receives and/or utilizes a DSL service and/or Internet services.
Additionally, as used herein, the term “DSL” refers to any of a variety and/or variant of DSL technology such as, for example, Asymmetric DSL (ADSL), High-speed DSL (HDSL), Symmetric DSL (SDSL), and/or Very high-speed DSL (VDSL). Such DSL technologies are commonly implemented in accordance with an applicable standard such as, for example, the International Telecommunications Union (ITU) standard G.992.1 (a.k.a. G.dmt) for ADSL modems, the International Telecommunications Union (ITU) standard G.992.3 (a.k.a. G.dmt.bis, or G.adsl2) for ADSL2 modems, the International Telecommunications Union (ITU) standard G.992.5 (a.k.a. G.adsl2plus) for ADSL2+ modems, the International Telecommunications Union (ITU) standard G.993.1 (a.k.a. G.vdsl) for VDSL modems, the International Telecommunications Union (ITU) standard G.993.2 for VDSL2 modems, the International Telecommunications Union (ITU) standard G.994.1 (G.hs) for modems implementing handshake, and/or the ITU G.997.1 (a.k.a. G.ploam) standard for management of DSL modems.
In the interest of brevity and clarity, throughout the following disclosure references will be made to connecting a DSL modem and/or a DSL communication service to a customer. However, while the following disclosure is made with respect to example digital subscriber line (DSL) equipment, DSL services, DSL systems and/or the use of ordinary twisted-pair copper telephone lines for distribution of DSL services, it should be understood that the disclosed methods and apparatus to characterize and/or test a transmission medium for communication systems disclosed herein are applicable to many other types and/or variety of communication equipment, services, technologies and/or systems. For example, other types of systems include wireless distribution systems, wired or cable distribution systems, coaxial cable distribution systems, Ultra High Frequency (UHF)/Very High Frequency (VHF) radio frequency systems, satellite or other extra-terrestrial systems, cellular distribution systems, power-line broadcast systems and/or fiber optic networks. Additionally, combinations of these devices, systems and/or networks may also be used. For example, a combination of twisted-pair and coaxial cable connected by a balun, or any other physical-channel-continuing combination such as an analog fiber to copper connection with linear optical-to-electrical connection at an optical network unit (ONU) may be used.
It will be readily apparent to persons of ordinary skill in the art that connecting a DSL modem and/or tester to a customer involves, for example, communicatively connecting the DSL modem and/or tester operated by a communications company to a telephone line (i.e., a subscriber line) that is communicatively connected to a second DSL modem and/or tester located at and/or in a customer premises (e.g., a home and/or place of business owned, leased or otherwise occupied and/or utilized by the customer). The second DSL modem and/or tester may be further communicatively connected to another communication and/or computing device (e.g., a personal computer) that the customer operates to access a service (e.g., Internet access) via the first and second DSL modems and/or tester, the telephone line and the communications company.